Increasing footprint of climate warming on flash droughts occurrence in Europe

Abstract

Flash droughts are caused by a rapid depletion of soil moisture, which severely affect vegetation growth and agricultural production. Notwithstanding the growing importance of flash droughts under the warming climate, drivers of flash droughts across the Europe are not well understood. Here we estimate the changes in flash droughts characteristics across Europe using the latest release of ERA5 reanalysis for 1950--2019 period. We find a substantial increase in the frequency and spatial extent of flash droughts across Europe (with 79\% of the total area) during the growing season with at-least one fourth of domain showing two-fold increase in the recent decades. Increased occurrence of flash drought is largely attributed to frequent occurrence of warmer and drier co-occurring events, with a sharp gradient of changes being noticed in Mediterranean and Central European regions. Compound meteorological extremes causing the flash drought events across Europe are pre-dominantly driven by the recent climate warming. With unabated greenhouse gas emissions and current pace of climate warming, Europe is likely to face an increased occurrence of flash droughts, requiring prompt response for effective drought adaptation and management strategies.

Flash drought drives rapid vegetation stress in arid regions in Europe

“…Multiple approaches have been suggested to identify flash drought based on various variables reflecting the rapid depletion of soil moisture [28]. Soil moisture quantile is one of the widely-used indices to identify flash droughts [8,9,12,13,27]. Soil moisture measurements are, however, often sparsely available in space.…”

“…Soil moisture measurements are, however, often sparsely available in space. Due to this reason, modelled soil moisture (reanalysis) or alternative variables such as evaporative stress index have been used in previous studies [9,12,27]. Here we overcome this limitation by using gap-free multi-layer soil moisture data, SoMo.ml, derived from machine learning trained with in-situ soil moisture [29].…”

“…Here, we assess the impact of flash droughts on terrestrial ecosystems in Europe between 2001 and 2019 using diverse observational gridded datasets derived from remote sensing and in-situ measurements. While a recent study showed the widespread occurrence of flash droughts across Europe [27], an assessment of the impact of these events is still lacking. We identify flash drought events at a 0.25 • resolution based on soil moisture percentiles, and then compare the temporal evolution of ecosystem variables between different climate regimes (i.e.…”

Enhanced trends in spectral greening and climate anomalies across Europe

“…Droughts are among the most severe environmental disasters, enhancing ecological and socio-economic conflicts (Geist & Lambin, 2004 ; Godfray et al, 2010 ; Gupta et al, 2020 ; Kaczan & Orgill-Meyer, 2020 ; Lambin & Geist, 2006 ; Lesk et al, 2016 ; Naumann et al, 2021 ; Schmidhuber & Tubiello, 2007 ; Xu et al, 2020 ). Particularly, long-term drought spells, hot drought events, flash droughts, and mega-heatwaves like in 2003, 2010, between 2018 and 2020, and recently in summer 2022 provoke persistent landcover transformations that amplify faunal and floral aggravation and land degradation, and consequently force socio-cultural adaptation (Barriopedro et al, 2011 ; Fischer et al, 2021 ; Ionita & Nagavciuc, 2021 ; Lin et al, 2020 ; Luterbacher et al, 2004 ; Miralles et al, 2014 ; Pereira et al, 2017 ; Quesada et al, 2012 ; Rasmijn et al, 2018 ; Schumacher et al, 2019 ; Shah et al, 2022 ; Sousa et al, 2020 ; Zhou et al, 2019 ). Parallel to this, the number of severe flood events and the frequency of wet spells increased over the past decades with significant regional variability across Europe (Breinl et al, 2020 ; Dai et al, 1998 ; Dietze et al, 2022 ; Kahle et al, 2022 ; Zolina et al, 2010 ).…”

“…The development of rapidly occurring and long-lasting extremes poses particularly high challenges on the ecosystem’s adaptive mechanisms. Due to the accelerated speed, intensification, and persistence of dry and wet spell transitions, severe water shortages or massive oversupply occur within short-term periods (Shah et al, 2022 ). Recent results, for example, by Fischer et al ( 2021 ), emphasized the strong increase in climate extremes probability and the short return periods of record-shattering events predicted for the next decades (Fischer et al, 2021 ).…”